Officials said Friday's raids by helicopters in the Persian Gulf saw two Greek oil tankers being seized by Iran's paramilitary Revolutionary Guard. Officials said the action was in retaliation to Athens' help in the U.S. seize of crude oil from an Iranian flagged tanker in the Mediterranean Sea this week. This was in violation of the harsh sanctions imposed by Washington on the Islamic Republic.

As tensions continue to rise between Iran and the West due to its broken nuclear agreement with world powers, the raid is the first major incident at sea for months. As Tehran increases its uranium enrichment, bringing it closer to weapons-grade levels than ever, there are growing concerns that negotiators will not find a way to reopen the agreement, increasing the risk of an even wider war.

The Guard released a statement in which it announced the seizure of the oil tankers and accused them of unspecified violations. Nour News, an Iranian website that is close to the Supreme National Security Council, warned that Tehran would take "punitive actions" against Greece for aiding the U.S. to seize oil from the Iranian-flagged ship Lana.

The Foreign Ministry of Greece said that it had made a strong protest to the Iranian ambassador in Athens regarding the "violent takingover" of two Greek-flagged vessels in the Persian Gulf. A ministry statement stated that "these acts effectively amount to acts piracy."

The ministry demanded the immediate release the vessels and crews. It warned that the seizure could have "particularly adverse consequences" for bilateral relations as well as Iran's relations to the European Union (of which Greece is a member).

According to the ministry, an Iranian helicopter crashed onto the Greek-flagged Delta Poseidon in international water, 22 nautical miles from Iran's coast.

It stated that "Armed men then captured the crew captive" and added that two Greek nationals were also among the crew.

The ministry reported that a similar incident was reported on a Greek-flagged ship carrying seven Greek citizens. It was located close to Iran's coast.

An official from Greece identified the second ship as The Prudent Warrior. He spoke on condition of anonymity in order to talk about details of the attack with journalists. Polembros Shipping in Greece earlier stated that the company was cooperating with authorities and making every effort to resolve the situation.

Officials from Greece did not identify the nationalities or crew members of the vessels.

According to MarineTraffic.com tracking data, both vessels were loaded with crude oil from Iraq's Basra terminal.

According to a U.S. defense official speaking under anonymity in order to discuss intelligence issues, it seemed that the two ships had approached -- but not into -- Iranian territory waters on Friday. They drifted into Iranian waters after the hijacking. Officials also stated that the ships had shut down their tracking devices, which was another red flag. The official stated that neither ship had sent a mayday nor a request for help.

Friday's Iranian seizure was the latest in a series of hijackings, explosions, and other incidents that have roiled a region that includes Strait of Hormuz. This narrow mouth of the Persian Gulf is through which half of all oil traded passes. These incidents started after Trump unilaterally pulled the U.S. out of Iran's nuclear agreement with world powers. This deal saw Tehran dramatically reduce its enrichment of Uranium in return for lifting economic sanctions.

The U.S. Navy attributed Iran to a number of attacks on tankers that were caused by limpet mines in 2019. It also blamed Iran for the fatal drone attack on an Israeli-linked tanker in which two crew members died in 2021.

Iranian hijackers stormed and briefly seized a Panama-flagged Asphalt Tanker off the United Arab Emirates last Year, as well briefly seizing and holding an Vietnamese tanker in November.

Tehran denies the attacks. However, a wider shadow conflict between Iran and the West has been playing out in volatile waters. Since 2019, tanker seizures have been part of it. In response to the United Kingdom's detention of an Iranian oil tanker off Gibraltar, Iran seized the British-flagged Stena Imero. The Iranian tanker was released months later, and the vessel was also released by London.

Last year, Iran also seized and detained a South Korean flagged tanker in a dispute over the Seoul's billions of dollars worth of frozen assets.